Vapor dispensing device

ABSTRACT

A device for diffusion of an active volatile substance into ambient air or closed spaces comprising a solid casing or housing and a solid carrier containing said volatile substance. The solid carrier is arranged in at least one recess formed in the housing, said recess having a depth and a width which are chosen in relation to the composition of the solid carrier so that the ratio of the evaporation surface of the solid carrier to the mass of the solid carrier is such that a substantially constant vapor release rate and total evaporation of said active volatile substance during the active lifetime of the device is obtained. The recesses can be of various geometrical shapes in order to give a pleasant appearance. The active volatile substance can be a perfuming, deodorizing, sanitizing composition or an insect repellent.

BACKGROUND OF THE INVENTION

The present invention relates to the field of perfumery. It relates,more particularly, to a device for diffusing perfume into thesurrounding air. The device of the invention, however, can also be usedfor the diffusion of other active volatile agents, such as insectrepellents, deodorizing or sanitizing agents, amongst others.

The use of various devices for the diffusion of volatile compounds, forexample perfumes, sanitizing agents, insect repellents, and the like,has become more and more current in recent years. For example,air-freshening devices or deodorizers are currently used in practicallyall households to mask bad odours or to impart fragrances to the ambientair. The known devices used for the diffusion of volatile compounds intothe surroundings make use of various principles. As an example, one canmention here dispersing devices of the spray type, aerosols ormechanical. Other examples include plastic packing elements enclosingthe active ingredients in liquid form. Typically, the diffusion of theactive ingredient takes place through membranes permeable to the vapoursof said ingredient.

One class of systems capable of diffusing active volatile ingredientsand which are of relevance with respect to the present invention aresolid state devices consisting of solid materials or carriersimpregnated with an active ingredient. Such devices may be formed ofvarious materials which are capable of absorbing the ingredient andsubsequently releasing it in a more or less controlled manner. Examplesof such known materials include gels, such as agar-agar or sodiumstearate gels, synthetic polymer resins, or blocks of mineral material,e.g. plaster or silica. It is even possible, for some purposes, to haveactive ingredients absorbed on paper or cardboard in order to obtain amore or less solid carrier device for diffusing the volatile ingredientthus absorbed. Often, solid devices are designed to be non-wetting, i.e.to be capable of effectively retaining the liquid active volatilematerial and only allowing the diffusion of the vapours of saidmaterial.

Solid state air-freshener devices have the advantage that they are easyto handle and may be shaped into various forms adapted to the customers'needs and desires. The devices can for example be in the form of a solidblock of a particular shape, e.g. a figure or a geometrical form, and beused as such. A material often used for such devices is plaster,allowing an easy shaping of the raw material into the desired form.

Solid state devices can also be placed into a housing in which they aretypically covered by a lid or a grill having openings to allow forcommunication between the surrounding air and the perfumed solid block,or they can be arranged between two grills. In these applications, thesolid perfumed block is covered by said lid or said grill and issometimes invisible from the outside of the packing. Unlike the unhousedair-fresheners, the appearance of the latter air-freshening devices isthat given by the housing or the grill, and it is therefore notnecessary, or not even possible, to shape the solid block into aparticular form to cause an aesthetic impression.

Solid block perfuming devices, however, generally have the drawback thatthe vapour release rate is not constant, but drops dramatically withinthe lifetime of the product. Furthermore, often the device is alreadyexhausted, i.e. no longer diffuses sufficient active ingredient, inspite of the fact that considerable amounts of active ingredient stillremain in the core of the block. This residual perfume, retained by thematerial of the block, is therefore entirely lost.

The object of the present invention is to provide a solid air-fresheningdevice for diffusing volatile substances, e.g. perfumes, insectrepellents, deodorizing or sanitizing agents, which is capable ofdiffusing said volatile substances at a relatively constant ratethroughout the lifetime of the device. Furthermore, the devices of theinvention are capable of releasing practically their entire content ofvolatile substance within their effective lifetime, such that verylittle active ingredient will be retained as a residue.

SUMMARY OF THE INVENTION

Accordingly, the present invention provides a device for the diffusionof an active volatile substance into ambient air or closed spacescomprising a solid casing or housing and a solid carrier containing saidvolatile substance wherein said solid carrier is arranged in at leastone recess formed in the housing, the at least one recess having a depthand a width which are chosen in relation to the composition of the solidcarrier containing the active substance so that the ratio of theevaporation surface of the solid carrier to the mass of the solidcarrier disposed within the said recess is such that a substantiallyconstant vapour release rate and total evaporation of said activevolatile substance during the active lifetime of the device is obtained.

The term “lifetime” in relation to the diffusion device of the presentinvention is used here to designate the period of time during which thedevice diffuses an amount of active ingredient sufficient to beeffective, i.e. which, for example, can be perceived in the case ofperfumes, or can remain active as insect repellent, deodorizing orsanitizing agent, and the like.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of an embodiment of a device according to theinvention;

FIG. 2 is a cross section view, along line 11—11, of the devicerepresented in FIG. 1; and

FIG. 3 represents a plan view of the same device once exhausted, i.e.once the perfume has been evaporated.

FIGS. 4 to 6 represent other embodiments of the device according to theinvention in the form of, respectively, a flower, a lemon and a disc.

DETAILED DISCLOSURE

The solid casing or housing of the device of the invention can be formedof any convenient material into which small-sized recesses can be cut ormoulded and which is adapted to be used as a bulk article. The materialshould thus be nontoxic and retain its form upon storage or use. Thematerial can, of course, show a certain flexibility. An importantcriterion for the choice of the appropriate material is itscompatibility with the solid carrier containing the volatile substance,such that the latter remains lodged in the recesses of the housing evenafter complete evaporation of the volatile substance.

Preferred materials for the housing or casing include wood, mineralmaterials (e.g. plaster), glass, or synthetic polymers (e.g. acrylic andmethacrylic polymers, polystyrene, polyesters, phenolic resins orsilicones). The solid housing may have any geometrical shape, forexample a cylinder, a prism, a pyramid, a tetrahedron, a cube or adiamond. The geometrical shape is preferably chosen to have a pleasantappearance.

According to a preferred embodiment of the invention, the housing orcasing is formed as a single block, having two substantially parallelfaces, the lower face being flat, and the recesses being cut or mouldedinto the upper face of the block.

The materials which can be used to form the solid carrier incorporatingthe volatile substance are the usual materials known in the art as beingappropriate carriers for the perfumes, or insect repellent, deodorizingor sanitizing agents or the like used according to the presentinvention. These carriers are capable of incorporating a considerableamount of active substance, typically between about 5 and 90% of theirtotal weight, and they are capable of retaining the active substance,i.e. the latter will not flow out of the carrier material in anyconsiderable amount, being intended to be released in the gaseous statefrom the carrier material into the surroundings of the air freshener.

Preferably, the solid carrier will be of a material capable of adheringto the housing or casing by itself. Whenever the carrier is made of amaterial which does not adhere sufficiently to the chosen housing, itmay be made to stay on the housing by means of e.g. an appropriate glueor polymer of synthetic or natural origin.

Non-limiting examples of appropriate carriers include plaster, silica,carboxymethylcellulose, wax-like materials (such as, for example,stearates or paraffins), alginates, carrageenans (such as, for example,agar-agar), paper, cardboard, synthetic polymers [such as, for example,polyacrylates, polymethacrylates or polyurethanes, polyethylene,ethylene-ethylacrylate copolymer, ethylene-vinyl acetate copolymer, apolyamide, a polyether block amide elastomer (e.g. Pebax®; origin: ElfAtochem)], polymer hydrogels (such as, for example, those disclosed inFR-A-2455068 or U.S. Pat. No. 4,362,841), or an hydrous polymer gels.

A preferred class of materials for the solid carrier incorporating thevolatile substance are anhydrous gels such as those described in U.S.Pat. No. 5,780,527 which are formed via the cross-linking of afunctionalised liquid polymer selected from maleinised polybutadiene ormaleinised polyisoprene, or a copolymer consisting of ethylene andmaleic anhydride, with a cross-linking agent which possesses one or morecomplementary functional groups, in the presence of a perfume,deodorizing or sanitizing base or of a surfactant agent. In a preferredembodiment, a functionalised liquid polymer selected from maleinisedpolybutadiene of molecular weight 5,000-20,000 or maleinisedpolyisoprene of molecular weight 200,000-500,000 is used. Suitablecross-linking agents include dihydroxypolybutadiene, ethoxylated orpropoxylated primary fatty amines, alkylpropyldiamines having anethoxylated or propoxylated higher aliphatic chain, diethanolamine,diethylenetriamine and polyoxyalkyleneamines, in particularpolyoxyalkylenediamines and -triamines. It is advantageous to use thefunctionalised liquid polymer and the cross-linking agent in a molarratio of approximately 1:1. In the most preferred embodiment, theanhydrous gel results from the in situ cross-linking between afunctionalised liquid polymer and a cross-linking agent consisting ofeither an oleylamine having 2 ethylene oxide units per molecule, acocoamine having 5 ethylene oxide units per molecule, orpolyoxyalkylenediamine or -triamine.

The gels which are obtained according to the above description arecapable of absorbing large amounts of an active, volatile ingredient,e.g. a perfume, an insect repellent, a deodorizing or sanitizing base orthe like.

The above-cited polymeric materials are all commercially available. Asexamples for maleinised polybutadiene or polyisoprene, one can cite theproducts known widely under the name of “Lithene®” [origin: RevertexLtd]. Amongst the different qualities of available Lithene®, goodresults have been obtained by using “Lithene® N4-9000 1OMA” [origin:Revertex Ltd]; 9000 stands for the molecular weight of polybutadienebefore maleinisation, whilst 1OMA indicates the degree ofmaleinisation—in this case 10 parts of maleic anhydride per 100 parts ofpolybutadiene (about 9.1%)—Lithene N4-B-1OMA, has also proven to beparticularly useful.

As examples of cross-linking agents, one can cite the following agents

alkylpropyldiamines having an ethoxylated or propoxylated higheraliphatic chain: products available under the name Dicrodamet (origin:Croda Chemicals Ltd)

ethoxylated or propoxylated primary fatty amines: Crodamet (origin:Croda Chemicals Ltd), in particular Crodamet 02 (oleylamine having 2ethylene oxide units per molecule) and Crodamet C5 (cocoamine having 5ethylene oxide units per molecule)

polyoxyalkylenediamines: Jeffamine® D and ED series (origin: HuntsmanCorporation), in particular Jeffamine® D-400, Jeffamine® EDR-148 andJeffamine® D2000

polyoxyalkylenetriamines: Jeffamine® T-403.

One can also cite polybutadiene having a hydroxylic function known asHFPB (origin: Revertex Ltd) which gelifies when admixed with maleinisedpolybutadiene. Sometimes, the use of specific catalysts allows bettercontrol of the gel formation and, to this end, there are used tertiaryamines (e.g.: DAMA 1010, a dialkylamine; origin: Albemarle SA). Mixturesof Hycar CTBN 1300×21, which is an amine terminated liquidbutadiene/acrylonitrile copolymer (origin: B.F. Goodrich), andmaleinised polybutadiene are also suitable.

As cited above, these anhydrous gels which are particularly adapted tobe used in the present invention, are described in U.S. Pat. No.5,780,527 (assignee: Firmenich SA).

An important feature of the present invention are the small-sizedrecesses formed in the solid casing or housing and containing thecarrier holding the active substance. In order to allow the desiredconstant vapour release and complete evaporation of the activesubstance, the recesses must be of a sufficiently small size and have anappropriate depth and width. In other words, the solid carrier arrangedwithin the recess and containing the active substance must have a highevaporation surface/mass ratio to allow sufficiently rapid diffusion ofthe active substance which it incorporates to the surface of the device,so as to ensure the constant and regular evaporation of said substance.However, the ratio between the evaporation surface and the mass of thesolid element should not be too high, in order to prevent a “burst-like”and rapidly declining release of the active substance, i.e. the recessmust not be too large or too shallow.

When in the above there is made mention of the evaporation surface/massratio, one can of course also use the evaporation surface/volume ratioin order to describe the same relationship, both values being easilyconvertible into each other via the density of the respective material.

A person skilled in the art will recognize that the appropriate size forthe recess has to be selected as a function of, for example, the natureof the material of the solid carrier and its porosity (which may varyfor a given material according to the mode of preparation), the amountof active ingredient and its volatility, or the interaction between thesolid carrier material and the active substance. All of these parameterscan have an impact on the efficiency of diffusion of the volatilesubstance and the appropriate size of the recesses can thus be readilydetermined on a case by case basis.

Recesses of many different forms can be used in the device of theinvention. As non-limiting examples, there are cited groove-, round-,oval-, square-, diamond-, star- or triangular-shaped recesses. Therecesses may have a constant or variable depth and/or a constant orvariable width. Generally, the geometrical form of the recesses is notcritical for the devices of the present invention, as long as these areof the appropriate size, as discussed above. Typical shapes can belabyrinth- or serpentine-like for example, without any vertical walls orseparations within the hollow volume of the recess.

When the device of the invention comprises several recesses, these canbe arranged so as to be isolated from each other or to be arranged in acommunicating manner. According to a preferred embodiment of theinvention, the solid support comprises several communicating grooves.

It is clear that for a recess of a given size, the evaporationsurface/mass ratio is considerably influenced by the height up to whichthe said recess is filled with the perfume-containing carrier. In apreferred embodiment of the invention, the recess or recesses are onlypartially filled with the solid carrier. The customer will thus notcontact the carrier during normal use of the device. In order to avoidsuch contact, the recesses of the device of the invention are small inshape and filled up to a degree which will not allow a user to touch thesolid carrier containing the active components with his fingers. Thisapplies likewise to adults' and babies' fingers, and in this manner thedevice of the invention has the advantage of complying with a variety ofsafety regulations.

The recesses may be shaped on only one surface of the support or,alternatively, on several of these, e.g. two opposite surfaces or facesof the support. Likewise, the recesses may be blind recesses or extendthrough the entire thickness or width of the casing or housing.Furthermore, multipiece devices may be formed, for example two singleface devices which are attached back to back.

The recesses of the housing of the present invention can be filled uppartially or entirely with the solid carrier or element containing thevolatile substance, via various methods which are known in the art. Forexample, the solid carrier material can be pressed mechanically into therecesses after having been prior impregnated with the volatilesubstance, e.g. perfume. This will be appropriate in the case of paperor cardboard being used as the carrier. Other methods include pouring,moulding or extrusion, which methods will be mainly applied when thecarrier holding the volatile active substance is made of a materialwhich originally is in the liquid state and is capable of solidifying orgelling after having been introduced into the recesses. Materialsshowing this property are for example plaster or synthetic polymers, inparticular the polymers disclosed in U.S. Pat. No. 5,780,527.

The overall surface of the solid carrier which is exposed to the air,after arrangement in the recess or recesses of the solid support,typically ranges from about 5 to 100 cm², preferably from about 10 to 50cm². Typical amounts of solid element range from about 2 g to 50 g,preferably from about 3 g to 30 g. The precise values for theabovementioned surface area and the amounts of solid element depend,amongst others, on the size of the diffusion device, the properties ofthe material of the housing or casing, e.g. its porosity or how muchactive ingredient it can incorporate, and the desired effect of thedevice.

In the case of the carrier materials as disclosed in U.S. Pat. No.5,780,527, the typical amount of carrier is from about 2 g to 20 g,preferably from about 3 g to 10 g.

A particular advantage of the device of the present invention lies inthe possibility of forming recesses of various forms into said housingor casing or arranging these in various manners. In this way, thepresent invention allows the formation of geometrical shapes orarrangements on one or more of the faces or surfaces of the supportdesigned to be exposed to the air, so as to give a pleasant andaesthetic impression to the user. The device can also be adapted tovarious tastes and preferences. The solid carrier containing thevolatile substance plays an active role in the visual impressionimparted to the consumer. However, unlike in other applications in whicha solid, volatile substance containing material is shaped into a certaingeometrical form and used as such as a diffusion device, the presentinvention makes it possible to obtain devices which are freely shaped asdesired, but in which the user can be protected from touching, orgetting into contact with, the solid carrier of the volatile substanceeven when the device is activated. As well as random geometric shapes,symmetrical patterns may be formed or a logo, brand name or word couldbe formed by the recesses of the device.

When the diffusion device of the present invention comprises the solidgel element disclosed in U.S. Pat. No. 5,780,527, the device has thefurther advantage that the gel can provide an end point indication ofexhaustion of its activity, i.e. when all of the active substance hasevaporated and the device no longer has any perfuming activity. This endpoint cue is provided by the shrinkage of the gel material, within therecess or recesses, which is perfectly visible. Often, also a crackingor tearing of the gel material is observed. This is particularly thecase when the device of the invention comprises recesses in the form ofgrooves which are arranged in a communicating manner.

When the diffusion device of the present invention is unactivated, asfor example during storage and before use, at least the surface in whichthe grooves were carved is covered by an appropriate material,impermeable to the vapours of the active substance, e.g. aluminum foil,in order to avoid evaporation of the active volatile substances. Uponactivation of the device to diffuse the volatile substance, the aluminumfoil or other protecting material, impermeable to the vapours of thelatter, shall be removed.

As a perfume base there can be used in the device of the invention anycomposition currently used in perfumery. The latter can be made ofdiscreet chemicals; more often, however, it will be a more or lesscomplex mixture of volatile liquid ingredients of natural or syntheticorigin. The nature of these ingredients can be found in specializedbooks of perfumery, e.g. in S. Arctander (Perfume and Flavor Chemicals,Montclair N.J., USA 1969) or similar textbooks of reference.

Although special mention has been made hereinabove of the perfumingeffect exerted by the invention device, the same principles apply to themanufacture of analogous devices for the diffusion of deodorizing orsanitizing vapours, the perfume base being then replaced by adeodorizing composition, a bactericide, an insecticide, a repellent oreven an attractant. By the term “sanitizing”, we refer here not only tothose substances which can enhance the degree of acceptance of thesurrounding air by an observer, but also to those substances which canexert an attractant or repellent effect towards certain species ofinsects, for instance towards houseflies or mosquitoes, or else whichcan have bactericide or bacteriostatic activity. It goes without sayingthat mixtures of such agents can also be used.

The invention will now be described in greater detail by way of thefollowing non-limiting examples, in which the abbreviations have themeanings known in the art and the temperatures are indicated in degreescentigrade, and with reference to FIGS. 1 to 3.

EXAMPLE 1 Manufacture of the Housing or Casing

A cylindrical, one-piece block having a flat lower face and an upperface provided with at least one recess was manufactured frompolymethylmethacrylate (PMMA) by a method known in the art such as, forexample, casting, moulding, injection-moulding, or other. The recessesin the disc can be formed for example simultaneously with themanufacture of the disc itself via an appropriate mould, or may be cutmechanically into the block prepared beforehand. The recesses will thenbe filled up with the carrier containing the volatile active substance.

FIGS. 1 and 2 show a preferred embodiment of the above-described disc(1) having an edge (4) and grooves (2) carved in a wavy form. The discas shown in FIGS. 1 and 2 can be filled with any appropriate solidcarrier material (3), described above and in the Example below andcontaining any appropriate perfume or other volatile substance, such asthose described below in examples 2 to 11. The disc (1) according to theFigures can for example have a diameter of about 7 cm, a thickness ofabout 17 cm, the grooves (2) having a depth of about 0.5 cm and a widthvarying between about 0.2 and 0.4 cm. The edge (4) has a width of about0.5 cm. The amount of solid carrier incorporated and prepared accordingto any of examples 2 to 11 is from 5 to 7 g, generally about 6 g,resulting in an evaporation surface of from 16 to 20 cm², and generallyabout 18 cm².

When the solid element in the grooves is a material prepared asdescribed in Examples 2 to 11, the diffusion device provides an endpoint indication when the device becomes inactive, i.e. no longercontains any significant amount of perfume. The material does in factcrack at this point and this is visible to the user and specificallyshown in FIG. 3.

EXAMPLE 2

2.23 g of Lithene N4-9000 1OMA and 10.28 g of a perfume base (Splash115.032 BGE origin: Firmenich SA, Geneva, Switzerland) were manuallymixed in an appropriate vessel. 0.34 g of Crodamet 02 were then addedunder stirring. The fluid mixture was then filled into the recess of asolid support of the invention, such as the one described in Example 1.After about 10 min at room temperature, the resulting polymer oilgelled, encapsulating the perfume base. Gel setting was complete inabout half an hour, after which the gel remained set within the casingrecesses.

EXAMPLE 3

3.54 g of Lithene® N4-B-1OMA and 6.87 g of a perfume base (Summerfruits150335F; origin: Firmenich SA, Geneva, Switzerland) were manually mixedin an appropriate vessel until the Lithene® had completely dissolved. Ina separate vessel 0.63 g of Jeffamine® D-400 was mixed with 9.79 g ofthe aforementioned perfume base. The Jeffamine/perfume mixture was thenadded to the Lithene®/perfume mixture under stirring. 6.25 g of theresulting fluid composition was then filled into the recess of a solidsupport of the invention (see FIG. 1). After about 30 minutes at roomtemperature the oil mixture had gelled.

When allowed to stand at ambient temperature the device evaporated >3 gof perfume in 42 days, after which time the gel had cracked.

Similar results were obtained using Green Apple 150123 (origin:Firmenich SA, Geneva, Switzerland) and Tropical 438874 (origin:Firmenich SA, Geneva, Switzerland) as perfume bases, used in the gel ata concentration of 80% w/w.

EXAMPLE 4

3.97 g of Lithene® N4-B-1OMA and 7.71 g of a perfume base (Summerfruits150335F; origin: Firmenich SA, Geneva, Switzerland) were manually mixedin an appropriate vessel until the Lithene® had completely dissolved. Ina separate vessel 0.70 g of a cross-linking mixture (comprising 70.00%w/w Jeffamine® D-400, 11.10% w/w Jeffamine® EDR-148 and 18.90% w/wdiethylphthalate) was mixed with 10.98 g of the aforementioned perfumebase. The cross-linking/perfume mixture was then added to theLithene/perfume mixture under stirring. 6.25 g of the resulting fluidcomposition was then filled into the recess of a solid support of theinvention (see FIG. 1). After about 10 minutes at room temperature theoil mixture had gelled.

When allowed to stand at ambient temperature the device evaporated >3 gof perfume in 42 days, after which time the gel had cracked.

EXAMPLE 5

1.44 g of Lithene® N4-9000 1OMA were mixed by hand in a beaker with14.93 g of a perfume base (Splash 115.032 BGE; origin: Firmenich SA,Geneva, Switzerland), whereupon 0.22 g of Crodamet 02 were added understirring. The mixture was filled into the recess of a solid casing ofthe invention of the type as described in Example 1. After 40 min, themixture gelled. The product was fully cured after approximately 3 h andremained set within in the casing recesses.

EXAMPLE 6

3.70 g of Lithene® N4-B-1OMA and 6.75 g of a perfume base (Peach & Apple140524; origin: Firmenich SA, Geneva, Switzerland) were manually mixedin an appropriate vessel until the Lithene had completely dissolved. Ina separate vessel 0.48 g of Jeffamine® T403 was mixed with 9.97 g of theaforementioned perfume base. The Jeffamine/perfume mixture was thenadded to the Lithene®/perfume mixture under stirring. 6.25 g of theresulting fluid composition was then filled into the recess of a solidsupport of the invention (see FIG. 1). After about 25 minutes at roomtemperature the oil mixture had gelled.

When allowed to stand at ambient temperature the device evaporated >3 gof perfume in 30 days, after which time the gel had cracked.

EXAMPLE 7

2.54 g of Lithene® N4-9000 1OMA and 6.23 g of a perfume base (Terminator109365B origin: Firmenich SA, Geneva, Switzerland) were mixed by handand 0.13 g of Crodamet 02 (ratio: Lithene®/Crodamet ca.3:1) were addedthereto under stirring. The mixture was filled into the recess of asolid casing of the invention, of the type as described in Example 1.The resulting oil gelled in 15 min at ambient temperature.

EXAMPLE 8

By proceeding as indicated in the previous example but using a molarratio of Lithene®/Crodamet of 5:1 instead of 3:1, a sticky gel wasobtained which lacked a certain degree of rigidity. The mixture wasfilled into the recess of a solid casing of the invention, of the typeas described in Example 1.

EXAMPLE 9

1.87 g of Lithene N4-9000 1OMA were mixed with 5.69 g of a perfume base(Terminator 109365B; origin: Firmenich SA, Geneva, Switzerland),whereupon 0.57 g of Crodamet 02 were added thereto under manualstirring. The mixture was filled into the recess of a solid using of theinvention, of the type as described in Example 1. After approximately 20min at room temperature, the oil gelled.

EXAMPLE 10

Approximately 2 g of Lithene® N4-9000 1OMA were placed in a beaker andmixed with the required amount of a perfume base (Honeysuckle 150061;origin: Firmenich SA, Geneva, Switzerland) until complete solution. Thecross-linking agents were pre-mixed and added under stirring to theperfume polymer base. The mixture was filled into the recess of a solidcasing of the invention, of the type as described in Example 1.

% w/w Honeysuckle 150061 80.00 80.00 80.00 80.00 % w/w Lithene ® N4-900017.14 17.49 17.85 18.24 10MA % w/w Jeffamine ® D-400  2.86 2.27 1.661.01 % w/w Jeffamine ® EDR-148 — 0.24 0.49 0.75 Gelling time (min) 59.0033.00 21.00 7.00

EXAMPLE 11

1.55 g of Lithene® N4-9000 1OMA were poured into an appropriatecontainer and mixed with 3.82 g of a perfume base (Lavender de Provence150060 (origin: Firmenich SA, Geneva, Switzerland) until completesolution.

In a separate beaker, 1.87 of Hycar CTBN 1300×21 (origin: B.F. Goodrich)were dissolved in 4.13 g of the same perfume base, and 5.37 g of thissolution were added to the previously obtained perfumed solution of thepolymer. The mixture was filled into the recess of a solid casing of theinvention, of the type as described in Example 1. A dry and rigid gelformed rapidly at ambient temperature.

What is claimed is:
 1. A device for diffusion of an active volatilesubstance into ambient air or closed spaces, said device comprising acasing or housing and a solid carrier containing said volatilesubstance, wherein said solid carrier is arranged in at least one recessformed in the casing or housing, said recess having a depth and a widthwhich are chosen in relation to the composition of the solid carriercontaining the active substance so that the ratio of the evaporatingsurface of the solid carrier to the mass of the solid carrier is suchthat, during the active lifetime of the device, a substantially constantvapour release rate and total evaporation of said active volatilesubstance are obtained.
 2. A device as claimed in claim 1, wherein thecasing or housing is formed as a single block.
 3. A device as claimed inclaim 2, wherein the casing or housing has two faces, one face beingflat the and the at least one recess being cut or moulded in the otherface thereof.
 4. A device as claimed in claim 5 wherein the at least onerecess is in the form of a square, a circle, a diamond, a triangle, astar, an oval or a groove.
 5. A device as claimed in claim 4 wherein therecess is in the form of a plurality of grooves.
 6. A device as claimedin claim 5 wherein the solid carrier comprises several communicatinggrooves.
 7. A device as claimed in claim 1 wherein the solid carrier ismade from wood, a mineral material or a synthetic polymer.
 8. A deviceas claimed in claim 7 wherein the solid carrier comprises plaster,glass, acrylic or methacrylic polymers, polystyrene, polyester, aphenolic resin or a silicone resin.
 9. A device as claimed in claim 1wherein the solid carrier containing the volatile substance comprisesplaster, silica, carboxymethylcellulose, a stearate, a paraffin, analginate, a carrageenan, agar-agar, paper, cardboard, a syntheticpolymer, a polymer hydrogel or an anhydrous polymer gel.
 10. A device asclaimed in claim 9, wherein the solid carrier is a synthetic polymerselected from the group consisting of a polyacrylate, apolymethacrylate, a polyurethane, a polyethylene, anethylene-ethacrylate copolymer, an ethylene-vinyl acetate copolymer, apolyamide and a polyether block amide thermoplastic elastomer.
 11. Adevice as claimed in claim 9, wherein the solid carrier is an anhydrouspolymer gel which results from the in situ cross-linking of afunctionalised liquid polymer selected from the group consisting ofmaleinised polybutadiene, maleinised polyisoprene and a copolymerconsisting of ethylene and maleic anhydride, with a cross-linking agentwhich possesses one or more complementary functional groups, in thepresence of a perfume, of a deodorizing or sanitizing base or of asurfactant agent.
 12. A device as claimed in claim 11 wherein thefunctionalised polymer is selected from the group consisting ofmaleinised polybutadiene of MW 5,000-20,000 and maleinised polyisopreneof MW 200,000-500,000.
 13. A device as claimed in claim 11 wherein thecross-linking agent is selected from the group consisting ofdihydroxypolybutadiene, ethoxylated or propoxylated primary fattyamines, alkylpropyldiamines having an ethoxylated or propoxylated higheraliphatic chain, diethanolamine or diethylenetriamine, andpolyoxyalkyleneamines.
 14. A device as claimed in claim 13 wherein thecross-linking agent is an oleylamine having 2 ethylene oxide units permolecule, a cocoamine having 5 ethylene oxide units per molecule, or apolyoxy-alkylene-diamine or -triamine.
 15. A device as claimed in claim11, wherein the functionalised liquid polymer and the cross-linkingagent are present in a molar proportion of 1:1.
 16. A device as claimedin claim 1, wherein the active volatile substance is a perfume, adeodorizing or sanitizing agent or an insect repellent.
 17. A device asclaimed in claim 1 wherein the at least one recess has a depth of about0.5 cm and a width of from 0.2 to 0.4 cm.
 18. A device as claimed inclaim 1 wherein the at least one recess has a surface area of from 10 to50 cm².
 19. A device as claimed in claim 18 wherein the at least onerecess has a surface area of from 16 to 20 cm².
 20. A device as claimedin claim 1 wherein the amount of solid carrier containing the volatilesubstance at the beginning of the lifetime of the device is from 3 to 30g.
 21. A device as claimed in claim 20 wherein the amount of solidcarrier containing the volatile substance at the beginning of thelifetime of the device is from 5 to 10 g.